Power modules are used for controlling main power (power controlling) in wide variety of apparatuses from industrial apparatuses to home electronics and information terminals. One set of examples of the power modules include inverters for converting DC power into AC power, and the like. Since such power modules are to be operated under a large current and a high voltage, it is thought to be essential that they ensure high electrical insulation and that they allow heat generated due to the operation to efficiently escape outside the power modules.
For example, in Patent Document 1, a power semiconductor device (power module) is disclosed in which multiple power semiconductor elements (power elements) are bonded to a heat dissipation plate by using a solder and are encapsulated by a molded resin enclosure. The power semiconductor device of Patent Document 1 is sandwiched between: a retainer plate that is placed on an upper surface of the molded resin enclosure; and a heat-dissipation fin (heatsink) that is in contact, through a thermally conductive grease, with the bottom surface where the heat dissipation plate (metal base) is exposed; and the power semiconductor device is fixed to the heat dissipation fin by means of a bolt inserted in a through-hole formed in the retainer plate, the molded resin enclosure and the heat dissipation plate. Further, in the power semiconductor device of Patent Document 1, respective one ends of a plate-like wiring member (lead frame) connected to electrodes of the multiple semiconductor elements, are projecting, as outside electrodes, from lateral surfaces of the molded resin enclosure. The front surface electrodes of the semiconductor elements are connected to the wiring member by way of wires and the rear surface electrodes of the semiconductors are connected to the wiring member by way of the heat dissipation plate. Meanwhile, in each of a semiconductor module (power module) in Patent Document 2 and a power module in Patent Document 3, respective end portions of an exposed material member exposed at the surface placed toward the heat dissipation plate, are each covered with an encapsulation resin to form a rib.